package com.sjh.baseui.widget;

import android.content.Context;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.widget.OverScroller;
import androidx.coordinatorlayout.widget.CoordinatorLayout;
import androidx.core.view.ViewCompat;
import com.google.android.material.appbar.AppBarLayout;
import java.lang.reflect.Field;
import static android.view.KeyEvent.ACTION_DOWN;

/**
 * 解决CoordinatorLayout+AppBarLayout滑动抖动问题
 *
 *
 *  用法    xml   在 AppBarLayout滑动抖动问题 添加属性   app:layout_behavior="com.yzjt.lib_app.widget.FlingBehavior"
 *
 * @author ysj
 * @date 2020/9/4 11:39
 */

/**
 * @author: wang_kita
 * @email: 357545619@qq.com
 * @date: 2020/7/29
 *
 * 解决 CoordinatorLayout+AppBarLayout+viewpager滑动抖动问题
 * 方案：AppBarLayout 设置FlingBehavior
 * 参考 https://blog.csdn.net/weixin_30869099/article/details/99175588
 */
public final class FlingBehavior extends AppBarLayout.Behavior {

    private static final String TAG = "FixBehavior";
    private static final int TYPE_FLING = 1;
    private boolean isFlinging;
    private boolean shouldBlockNestedScroll;

    public FlingBehavior(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    public boolean onInterceptTouchEvent(CoordinatorLayout parent, AppBarLayout child, MotionEvent ev) {
        shouldBlockNestedScroll = isFlinging;
        switch (ev.getActionMasked()) {
            case MotionEvent.ACTION_DOWN:
                //手指触摸屏幕的时候停止fling事件
                stopAppbarLayoutFling(child);
                break;
            default:
                break;
        }
        return super.onInterceptTouchEvent(parent, child, ev);
    }

    /**
     * 反射获取私有的flingRunnable 属性，考虑support 28以后变量名修改的问题
     * @return Field
     */
    private Field getFlingRunnableField() throws NoSuchFieldException {
        Class<?> superclass = this.getClass().getSuperclass();
        if(superclass == null) return null;
        Class<?> baseBehaviorType = superclass.getSuperclass();
        if(baseBehaviorType == null) return null;
        Class<?> headerBehaviorType = baseBehaviorType.getSuperclass();
        if(headerBehaviorType == null) return null;

        try {
            return headerBehaviorType.getDeclaredField("flingRunnable");
        } catch (NoSuchFieldException e) {
            e.printStackTrace();
        }

        try {
            return headerBehaviorType.getDeclaredField("mFlingRunnable");
        } catch (NoSuchFieldException e) {
            e.printStackTrace();
        }

        return null;

    }

    /**
     * 反射获取私有的scroller 属性，考虑support 28以后变量名修改的问题
     * @return Field
     */
    private Field getScrollerField() throws NoSuchFieldException {
        Class<?> superclass = this.getClass().getSuperclass();
        if(superclass == null) return null;
        Class<?> baseBehaviorType = superclass.getSuperclass();
        if(baseBehaviorType == null) return null;
        Class<?> headerBehaviorType = baseBehaviorType.getSuperclass();
        if(headerBehaviorType == null) return null;

        try {
            return headerBehaviorType.getDeclaredField("scroller");
        } catch (NoSuchFieldException e) {
            e.printStackTrace();
        }

        try {
            return headerBehaviorType.getDeclaredField("mScroller");
        } catch (NoSuchFieldException e) {
            e.printStackTrace();
        }

        return null;
    }

    /**
     * 停止appbarLayout的fling事件
     * @param appBarLayout
     */
    private void stopAppbarLayoutFling(AppBarLayout appBarLayout) {
        //通过反射拿到HeaderBehavior中的flingRunnable变量
        try {
            Field flingRunnableField = getFlingRunnableField();
            Runnable flingRunnable;
            if (flingRunnableField != null) {
                flingRunnableField.setAccessible(true);
                flingRunnable = (Runnable) flingRunnableField.get(this);
                if (flingRunnable != null) {

                    appBarLayout.removeCallbacks(flingRunnable);
                    flingRunnableField.set(this, null);
                }
            }

            Field scrollerField = getScrollerField();
            if (scrollerField != null) {
                scrollerField.setAccessible(true);
                OverScroller overScroller = (OverScroller) scrollerField.get(this);
                if (overScroller != null && !overScroller.isFinished()) {
                    overScroller.abortAnimation();
                }
            }
        } catch (NoSuchFieldException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        }
    }

    @Override
    public boolean onStartNestedScroll(CoordinatorLayout parent, AppBarLayout child,
                                       View directTargetChild, View target,
                                       int nestedScrollAxes, int type) {

        stopAppbarLayoutFling(child);
        return super.onStartNestedScroll(parent, child, directTargetChild, target,
                nestedScrollAxes, type);
    }
    @Override
    public void onNestedPreScroll(CoordinatorLayout coordinatorLayout,
                                  AppBarLayout child, View target,
                                  int dx, int dy, int[] consumed, int type) {

        //type返回1时，表示当前target处于非touch的滑动，
        //该bug的引起是因为appbar在滑动时，CoordinatorLayout内的实现NestedScrollingChild2接口的滑动
        //子类还未结束其自身的fling
        //所以这里监听子类的非touch时的滑动，然后block掉滑动事件传递给AppBarLayout
        if (type == TYPE_FLING) {
            isFlinging = true;
        }
        if (!shouldBlockNestedScroll) {
            super.onNestedPreScroll(coordinatorLayout, child, target, dx, dy, consumed, type);
        }
    }

    @Override
    public void onNestedScroll(CoordinatorLayout coordinatorLayout, AppBarLayout child,
                               View target, int dxConsumed, int dyConsumed, int
                                       dxUnconsumed, int dyUnconsumed, int type) {

        if (!shouldBlockNestedScroll) {
            super.onNestedScroll(coordinatorLayout, child, target, dxConsumed,
                    dyConsumed, dxUnconsumed, dyUnconsumed, type);
        }
    }

    @Override
    public void onStopNestedScroll(CoordinatorLayout coordinatorLayout, AppBarLayout abl,
                                   View target, int type) {

        super.onStopNestedScroll(coordinatorLayout, abl, target, type);
        isFlinging = false;
        shouldBlockNestedScroll = false;
    }

}

